HINTS TO PLANT COLLECTORS. 



187 



two seasons, by being planted out in a rich border. Of course 

 such rapidity of growth is unfavourable to their flowering freely. 

 Many do not shift or pot their succulents above once in two, three, 

 or four years; niany kinds do not require it oftener, but they are 

 the small and slow-growing kinds, such as most of the melon-shaped 

 Cactece, &c. After most succulents have attained their full size, shifting 

 may be dispensed with oftener than while grov^dng, for most of them 

 flower best when they have ceased to grow rapidly. 



While revising the preceding pages for the press, we are in receipt of 

 the following interesting information on the habits and cultivation of the 

 CactecB from our respected friend Mr. Beaton, who, with his employer, Mr, 

 Harris, of Kingsbury, has paid more than ordinary attention to the sub- 

 ject. Mr. Hams is an enthusiastic patron of botanical pursuits, and has 

 been some time engaged in forming a collection, not of lining species 

 only, but also of dead specimens for his herbarium. 



In WTiting on the Cacti,^ says our correspondent, I hope you will 

 record your dissent from those who consider the sections into which the 

 old genus Cactus has been divided as distinct genera. Notliing can be 

 more incorrect, and nothing tends more to mystify the writings of our 

 best gardeners than thus follov^ng the dicta of the great men who have 

 the lead in Botanical science ; a zoologist might as well attempt to divide 

 the greyhound, bull-dog, or terrier, into distinct genera, as botanists to 

 divide the Mammillaria and others from the Cactus. Yet, into this error 

 Mr. Don has fallen {System of Botany, Vol. III. p. 157), when he describes 

 the Mammillaria as destitute of a woody axis or central column. All the 

 sections of the genus have not only a woody axis, but a medulliferous 

 column inside their woody axis, like other exogenous plants. 



" This axis, however, is not formed during the first few years of their 

 existence, and probably difl*erent species require diflerent periods to form 

 it; while in its turn it is .not at first suppUed with its medulla or 

 pith : both the woody axis and pith make their first appearance at the 

 collar of the plant at the point where the roots start from the stem. As 

 the axis increases it throws out fibres into all parts of the succulent por- 

 tion of the plant, and is the channel through which the nourishment is 

 supplied from the roots; and I am of opinion that the Melocactv^, Echino- 

 cactuSj and Mammillaria v^dll not form roots from cuttings until they first 



